Sukhoi4Me

We have a perfect day for flying today. While at the field last night cleaning up after flying, I noticed the inboard servo bay was loose. Couldn't work on it last night, so here I am this morning trying to figure it out. The servo mount is entirely loose in the foam wing. It wiggles from side to side and front to back but will not pull out because of the sheeting. Any ideas on how to glue it back in so its solid? I have never built foam wings so I am not sure what to do.. I know not to use CA unless its foam safe CA... Any suggestions????

Sukhoi4Me

Getting a few visitors, but no ideas... its gonna be a good day for flying... please help???

sailing1

My Feedback: (134)

I had one of the wing servos on my 35% Sukhoi come loose last year. I took the servo out and working one side at a time glued it back to the sheeting using regular CA from the inside of the servo cage. For the bottom side of the servo cage (tope side of the wing) I put it on a table, used a long tube to direct the glue and then put enought weight on the cage to make sure the glue set up correctly. For the top side of the cage I did pretty much the same but turned the wing over so the opening was on the down side when I got done glueing. I also used some weight on this step. I did not glue anything to the foam.

After the first one came loose I pulled all the servos out a little and added some "insurance glue" to all of the bays. I check the mounts from time to time but suspect on mine it just was never glued in correctly in the first place. I am not sure if this is the prescribed or right way to do this, but the Big Sukhoi is on it's second year with that repair and has never come loose again.

Sukhoi4Me

Good morning sailing1. I sent you a PM....

Ih82crash

If the wing is sheeted all you have to do is glue the mount to the sheeting just like Sukhoi says. should be an easy fix. If some CA gets on the foam and melts it it is not the end of the world.

krayzc-RCU

My Feedback: (31)

put some poly glue on it as it foams it will tighten all up.

Tired Old Man

My Feedback: (1)

You can't use regular ca on foam. It completely destrots the foam. Foam safe ca is extremely weak so that's not an alternative. Use either epoxy, working it under and around the servo plate or urethane glues as krayzc noted.

The most effective way, but not the fastest, would be to open up the wing, remove the sheeting in an area roughly an inch larger all around the servo plate, and re-glue the plate. Use some micro balloons to thicken some epoxy for filling any divots that may have been created in the foam during the removal process. If you have any high density foam around you can sand off some to use a powder mixed into the epoxy instead of micro balloons. Clean up any excess epoxy to eliminate bumps and ridges then you can epoxy some new sheeting back over the plate. You won't be flying today but the servo will be good to go for a lot of flying days after the repair.

Sukhoi4Me

Thanks for all the advice. Used CA for a quick fix, will do the permanent fix this evening. Will inject Gorilla glue all around to fill up any voids created by the CA. I was very careful with it and didn't use it wildly. Servo bays are now tight and not moving.

thaus

My Feedback: (2)

I had 3 servo boxes come loose the first day of flying the 35% Extra. I used thickend epoxy (Hysol) at the bottom of the box to attach the box to the wing sheeting, and gorilla glue forced into the gap at the top of the box to attach the top of the box to the sheeting. After 4 gallons of fuel, the servos are secure. A better treatment would be to use fiberglass and epoxy, instead of the Hysol.